The present invention relates to an apparatus and method for performing thrombolysis and, more particularly, is directed to an apparatus and method for delivering an infusate into a body lumen to dissolve thrombus.
Removal of thrombus from human vasculature may be accomplished via a traditional open surgical procedures, or via endovascular procedures. While open surgical procedures remain the standard for many cases, endovascular procedures are typically less invasive and often decrease the time between diagnosis and treatment. This is especially critical, for example, in lysis of a cerebrovascular clot for treatment of an acute stroke.
Current endovascular techniques for removing thrombus include mechanical and chemical approaches. Known mechanical approaches include perturbation of the thrombus via physical scraping, the application of a pressure gradient, and electromechanical stimulation. Known chemical approaches include intravenous (or systemic) delivery of a thrombolytic agent and selective delivery of a thrombolytic agent through an infusion catheter. It can be advantageous with both mechanical and chemical approaches to use a filter device to trap thrombus dislodged during the endovascular procedure and thereby prevent the dislodged thrombus from traveling downstream in the vasculature.
One of the challenges faced by surgeons using endovascular techniques to remove thrombus is the wide variation in size (axial length) of the thrombotic material. Thrombotic material in vasculature frequently ranges from 5 cm to 30 cm in axial length, requiring the surgeon to select an infusion catheter having the proper infusion length. Sometimes this selection process may occur prior to surgery, but other times the selection of the infusion catheter occurs during surgery, which requires an assortment of infusion catheters having various infusion lengths to be brought into surgery. Hence, a need exists for an infusion catheter in which the infusion length can be varied according to the size of the thrombus.
Another challenge faced by surgeons using endovascular techniques to remove thrombus arises when dislodged thrombus is trapped in a filter. The filter is typically inserted into the vasculature through a relatively small catheter. Often, the dislodged thrombus includes relatively large sections which make it difficult to retract a filter filled with such large sections of thrombus. Hence, a need exists for a thrombolysis apparatus which sufficiently reduces or, ideally, completely dissolves the thrombus trapped by the filter so that the filter can be easily retracted and removed.
The present invention is an apparatus for delivery of an infusate into a body lumen to perform thrombolysis. The apparatus comprises a catheter having an infusion section defined by a plurality of infusion ports for delivering the infusate. The infusion ports are spaced axially apart along the length of the infusion section. A sheath coaxially surrounds a portion of the catheter. The sheath is axially movable relative to the catheter to selectively uncover at least a portion of the infusion ports and thereby control the amount and distribution of the infusate delivered by the infusion section.
In accordance with another aspect, the present invention is an apparatus for dissolving thrombus in a body lumen. The apparatus comprises relatively movable first and second tubular members. The first tubular member is at least partially disposed coaxially within the second tubular member. The first tubular member has a plurality of infusion ports for directing the flow of a thrombolytic liquid. The infusion ports are spaced axially apart. At least a portion of the infusion ports are coverable by the second tubular member. An infusion section of the apparatus has an axial length that is variable. The infusion section is defined by an uncovered portion of the infusion ports. The axial length of the infusion section is varied by relative movement between the first and second tubular members, which changes the quantity of infusion ports in the uncovered portion of the infusion ports.
In accordance with yet another aspect, the present invention is an apparatus for dissolving thrombus in a body lumen. The apparatus comprises a catheter assembly having an infusion section with a variable axial length. The infusion section includes an axially spaced plurality of infusion ports for directing the flow of a thrombolytic fluid. The catheter assembly includes means for selectively covering a portion of the infusion ports to control the variable axial length of the infusion section and thereby control the distribution of thrombolytic fluid flow.
In accordance with still another aspect, the present invention is a method for dissolving thrombus in a body lumen. According to the inventive method, a catheter assembly having an infusion section with an adjustable axial length is provided. The infusion section includes a plurality of infusion ports for directing flow of a thrombolytic agent. The axial length of the infusion section is adjusted to a desired length based on the size and location of thrombotic material in a body lumen. The catheter assembly is inserted into the body lumen containing the thrombotic material and positioned so that the infusion ports lie adjacent the thrombotic material. A thrombolytic agent is then infused through the catheter assembly and the flow of the thrombolytic agent is directed against the thrombotic material to dislodge and dissolve the thrombotic material.